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--HG-- rename : content/media/omx/MP3FrameParser.cpp => content/media/MP3FrameParser.cpp rename : content/media/omx/MP3FrameParser.h => content/media/MP3FrameParser.h
77 lines
2.4 KiB
C++
77 lines
2.4 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include <stdint.h>
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#include "mozilla/Mutex.h"
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namespace mozilla {
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// A description of the MP3 format and its extensions is available at
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//
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// http://www.codeproject.com/Articles/8295/MPEG-Audio-Frame-Header
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//
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// The data in MP3 streams is split into small frames, with each frame
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// containing a fixed number of samples. The duration of a frame depends
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// on the frame's bit rate and sample rate. Both values can vary among
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// frames, so it is necessary to examine each individual frame of an MP3
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// stream to calculate the stream's overall duration.
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//
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// The MP3 frame parser extracts information from an MP3 data stream. It
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// accepts a range of frames of an MP3 stream as input, and parses all
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// frames for their duration. Callers can query the stream's overall
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// duration from the parser.
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//
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// Call the methods NotifyDataArrived or Parse to add new data. If you added
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// information for a certain stream position, you cannot go back to previous
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// positions. The parser will simply ignore the input. If you skip stream
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// positions, the duration of the related MP3 frames will be estimated from
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// the stream's average.
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//
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// The method GetDuration returns calculated duration of the stream, including
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// estimates for skipped ranges.
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//
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// All public methods are thread-safe.
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class MP3FrameParser
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{
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public:
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MP3FrameParser(int64_t aLength=-1);
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bool IsMP3() {
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MutexAutoLock mon(mLock);
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return mIsMP3;
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}
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void Parse(const uint8_t* aBuffer, uint32_t aLength, int64_t aOffset);
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void NotifyDataArrived(const char* aBuffer, uint32_t aLength, int64_t aOffset);
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int64_t GetDuration();
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private:
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size_t ParseInternalBuffer(const uint8_t* aBuffer, uint32_t aLength, int64_t aOffset);
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uint8_t mBuffer[10];
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uint32_t mBufferLength;
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// A low-contention lock for protecting the parser results
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Mutex mLock;
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// All fields below are protected by mLock
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uint64_t mDurationUs;
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uint64_t mBitRateSum;
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uint64_t mNumFrames;
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int64_t mOffset;
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int64_t mUnhandled;
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int64_t mLength;
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uint32_t mTrailing;
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// Contains the state of the MP3 detection
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bool mIsMP3;
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};
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}
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